The present invention relates to a dispensing apparatus. In particular, the present invention relates to an apparatus for dispensing abrasive particulate material into a stream of gas in a pipe for the purpose of cleaning the internal pipe walls and a method of cleaning internal pipe walls using such an apparatus.
Tubercles form as a result of corrosion inside steel and cast water mains and consist of layers of corrosion products, such as rust and the like, which build up over time to form lumps and mounds over local areas of metal loss.
Tubercles can severely reduce the internal bore of pipes, leading to reduced flow and a necessary increase in pumping pressure to maintain a supply of water though the pipe.
Current methods of removal of tubercles involve the use of steel flails, rotated inside the pipe on rotating rods, impacting the pipe wall and chipping off the tubercle growth. This method uses large quantities of water to flush away loosened tubercle debris from inside the pipe and this dirty waste water is dumped to surface drains, which is clearly not environmentally desirable. In addition, the physical action of the steel flails impacting the pipe wall can dislodge the pipe at the pipe joints, thereby causing leaks in the pipeline supply.
There are several existing methods of cleaning pipes which use material such as sand or rocks blown through a pipe to act as scourers to dislodge tuberculation thereby clearing debris from the internal pipe wall. However, such methods are often unsuccessful and they fail to deliver the material into the pipe in a measured and controlled way to ensure that there is effective cleaning whilst minimising/preventing damage to the internal walls of the pipe from impaction by the aggregate material.
There is therefore a need for an effective and reliable method of delivery of aggregate material into a pipe in a controlled manner so as to minimise/prevent damage to the internal walls of the pipe whilst maximising the cleaning of debris from the interior surfaces of the pipe during the cleaning process.